Hybrid steppers or servos?

Todd wrote:

If you are converting a machine that was using steppers to servos. I would recommend the hybrid closed loop steppers because, steppers have a very different speed/torque profile than a servo. Servos tend to need a much higher gear reduction than a comparable stepper. So to get the same performance you will likely need to change your gearing to match (probably something like 3-5x).

Teknic makes a servo product that is intended as stepper replacements (Clearpath-SD), but there are probably other more economic options out there.
www.teknic.com/products/clearpath-brushl...3EAAYASACEgIYB_D_BwE

Thank you very much for your advice Todd, it makes a lot of sense what you say, since I had something in mind that was to remove what I have and put on and I am seeing that I will only achieve that with closed loop steppers since the servos have ( usually) a larger frame, another shaft diameter, operation, etc ... My machine is direct drive and even without reduction I would have to change the coupling.

The Teknic that you mention I had seen on YouTube, the truth is that they are very appetizing but have prohibitive prices


Tommy thank you very much as always, don't worry I was joking, your opinion is always welcome. When you say Chinese, do you mean AliExpress? I have seen in a thread a colleague who recommends some and also indicates that it is a color to adjust them, keep in mind that I know absolutely nothing about servos and adjust them.

tommylight wrote:

RoberCNC wrote:

When you say Chinese, do you mean AliExpress? I have seen in a thread a colleague who recommends some and also indicates that it is a color to adjust them, keep in mind that I know absolutely nothing about servos and adjust them.

Yes, user named Bevins uses some of them that have proven pretty good, but they are much bigger than what you need.
If that is the case, stick to closed loop steppers, no tuning required!

Bevins that is. Well, yes, I think that given the limitations I will opt for a closed-loop stepper kit, it is what best suits my current limitations, switching to servos and everything that entails would almost mean making half a new machine, so to when I make the next one.

Any kit recommendations Tommy? I have seen some Wantai, like the drivers you told me, and the truth is that I am delighted with them.

BeagleBrainz wrote:

I just bought a servo driver setup to use as a spindle on my mill. I went directly through DMM, and am really happy with their kit.
Just bear in mind depending on the driver you use there is a lot more in the way of filtering and other gubbons that is recommended before the power gets to the servo drive.

Sorry BeagleBrainz I had not read your message, and forgive me again because I do not understand absolutely anything of what you comment.
DMM, gubbons? Pardon my ignorance.

robert

just wanted to chime in here

I use chinese servos on a 6 ton cnc mill. I get accuracy of about 0.005mm and the following error is tiny even at speed. I machine a lot of injection molds on it and they come out awesome.

I actually just bought another 8 servo drives for two more cnc machines here.

from yuhai servos in china. they have been really good to deal with.

www.zjyuhai.cn/en/

But as other people have said they are a pain to tune. they come with tuning software but I haven't been able to get it working.

I worked out a hack for those running step direction. if you have a 7i76 mesa card you can take the encoder feedback from the drives and then use the 7i76 spindle encoder counter to get it into linuxcnc. then tune them with halscope. changing values on the physical servo drive and graphing the following error in halscope. but my next machine is going to be analog 0-10 volts with a velocity loop in linuxcnc.. the support from bill at yuhai is awesome. can't fault it. he basicely taught me all about servos lol.

but for a first time user they are a bit of a pain. very good servo drives though and very affordable priced.

a matched 1kw drive and servo motor costs 200 usd. just for reference. they come roughly tuned and are not bad out of the box. but really need tuning again after you put them in the machine.

Yuhai also make all the stepper drives and closed loop stepper drives

better say that I am not connected with yuhai servos I suppose just a satisfied customer

regards

Andrew

Thank you very much for your contribution Becksvill. I appreciate any information in this regard and I am sure that more than one mate will find it very useful. Personally, the more I learn about servos the more I realize that I will have to settle for a closed loop, due to the size and my ignorance especially hahaha, due to mistakes made in the design they must be nema 23. Of course, I am learning a lot and taking lots of notes and future improvements.

Was thinking to give my view of this. Then I remembered that I did test with a 200W servo on my milling machine. I replaced a Nema32 closed loop servo with a servo and made a series of youtube videos on that. Fair disclaimer: not everything I say is necessarily correct, but that is how it came out anyways.



The link to the playlist is here

In the end I think I'm going to choose these, they comply with my restrictions, I shouldn't touch anything other than change one for another and also from what I've seen in some video they are configurable PC life (with its corresponding Rs232 to USB adapter of course)

What opinion do they deserve? Anyone who has tried them or has them and can tell me something?

www.ebay.co.uk/itm/Free-Ship-NEMA23-Clos...61-a23e-3d43d2f55464

Thanks..

hard to tell what you will get out of these motors? i was looking for a torque speed chart but it seems to not be included with the information in the link?

i would take a good look for that information before buying if it was me. the thing to watch out for is how much torque you loose when the motor is running at higher speeds.

as mentioned before the with DMM servo's and drives they are AC servo's so the cost goes up building the controls for these. because the dives require EMI filters and a line reactor on each drive to keep the power stable. this can add a lot of extra cost to building the controller, AC power is a little more complex compared to a DC system.

the hybrid systems are a step up from the open loop stepper systems but they are still just a semi closed loop that operate on the same limitations of the open loop steppers. the AC servo's systems have a much wider band of usable speed and torque compared to steppers.

I take note of Machinedude, in none of the ones I'm looking at does that info appear. What is your recommendation?